Carbon based bipolar plate coatings for effective water management

Abstract

A flow field plate for fuel cell applications includes a metal with a carbon layer disposed over at least a portion of the metal plate. The carbon layer is overcoated with a silicon oxide layer to form a silicon oxide/carbon bilayer. The silicon oxide/carbon bilayer may be activated to increase hydrophilicity. The flow field plate is included in a fuel cell with a minimal increase in contact resistance. Methods for forming the flow field plates are also provided.

What is claimed: 
     
       1. A flow field plate for fuel cell applications comprising:
 a metal plate having a first surface and a second surface, the first surface defining a plurality of channels for directing flow of a first gaseous composition; 
 a carbon layer disposed over at least a portion of the metal plate, the carbon layer being doped with a component selected from the group consisting of Pt, Ir, Pd, Au, Ag, Co, Fe, Cu, Si, Ti, Zr, Al, Cr, Ni, Nb, Hb, Mo, W, Ta, and N; and 
 a silicon oxide layer disposed over at least a portion of the carbon layer to form a silicon oxide/carbon bilayer, the silicon oxide/carbon bilayer having an activated surface including broken bonds and nitrogen. 
 
     
     
       2. The flow field plate of  claim 1  wherein the silicon oxide/carbon bilayer has a surface with a contact angle less than 40 degrees. 
     
     
       3. The flow field plate of  claim 1  wherein the contact resistance is less than 40 mohm-cm 2  when the flow field plate is sandwiched between carbon papers at 200 psi. 
     
     
       4. The flow field plate of  claim 1  wherein the silicon oxide layer is selectively deposited on a plurality of walls of the channels. 
     
     
       5. The flow field plate of  claim 1  further comprising one or more additional silicon oxide/carbon bilayers disposed over at least a portion of the silicone oxide/carbon bilayer. 
     
     
       6. The flow field plate of  claim 1  wherein the silicon oxide layer includes hydrocarbons in an amount that is less than 40 weight percent of a total weight of the silicon oxide layer. 
     
     
       7. The flow field plate of  claim 1  wherein the silicon oxide layer includes hydrocarbons in an amount that is less than 20 weight percent of a total weight of the silicon oxide layer. 
     
     
       8. The flow field plate of  claim 1  wherein the carbon layer comprises amorphous carbon. 
     
     
       9. The flow field plate of  claim 1  wherein the carbon layer comprises crystalline carbon. 
     
     
       10. The flow field plate of  claim 8  wherein the silicon oxide/carbon bilayer has a surface including on average at least 5 pores per cm 2 . 
     
     
       11. The flow field plate of  claim 8  wherein the silicon oxide/carbon bilayer has a surface roughness average from 200 to 1000 nm. 
     
     
       12. The flow field plate of  claim 1  wherein the second surface defines a second plurality of channels for directing flow of a second gaseous composition. 
     
     
       13. The flow field plate of  claim 1  wherein the second surface is a second non-crystalline carbon layer. 
     
     
       14. A fuel cell comprising:
 a first flow field plate comprising:
 a metal plate having a first surface and a second surface, the first surface defining a plurality of channels for directing flow of a first gaseous composition; 
 a carbon layer disposed over at least a portion of the metal plate, the carbon layer being doped with a component selected from the group consisting of Pt, Ir, Pd, Au, Ag, Co, Fe, Cu, Si, Ti, Zr, Al, Cr, Ni, Nb, Hb, Mo, W, Ta, and N; 
 a silicon oxide layer disposed over at least a portion of the carbon layer to form a silicon oxide/carbon bilayer, the silicon oxide/carbon bilayer having an activated surface including broken bonds and nitrogen; 
 
 a first catalyst layer disposed over the first flow field plate; 
 an ion conductor layer disposed over the first catalyst layer; 
 a second catalyst layer disposed over the ion conductor layer; and 
 a second flow field plate disposed over the second catalyst layer. 
 
     
     
       15. The fuel cell of  claim 14  having a contact resistance less than 40 mohm-cm 2  when the flow field plate is sandwiched between carbon paper at 200 psi. 
     
     
       16. The fuel cell of  claim 14  wherein the silicon oxide/carbon bilayer has a surface with a contact angle less than 30 degrees.